A semiconductor laser (laser diode) transforms electrical energy into optical energy with relatively high efficiency. A laser diode is typically includes a layer of p-type semiconductor material adjacent to a layer of n-type semiconductor material (referred to as a p-n junction). When electrical current passes from the p-type layer to the n-type layer, stimulated emission of optical radiation results in the active layer. In practice, the stimulated emission is limited to only the active layer. The opposing end faces of the active region are called the facets, which are cleaved and/or etched to define a laser cavity between the two facets. A highly reflective dielectric coating is usually deposited on one facet (the non-output facet), and a semi-reflective dielectric coating on the other facet (the output coupling facet). The optical energy generated by the electric current oscillates between the output facet and the non-output facet, and is partially transmitted by the semi-reflective coating at the output facet to produce a diode laser output beam.
The use of lasers has dramatically increased over the past few years. As the technology has matured, organizations have greatly increased its use of lasers. High-power beams from laser diodes are of interest in solid-state laser pumping and telecommunications. Many industrial and medical applications also required high power density to be delivered to a particular site or point.
Since diode lasers are obtainable at relatively low cost, is desirable to combine the output of several or many laser diodes in order to obtain a high-power laser beam. However there are several difficulties in doing this. Several methods have been developed to combine the output of laser diodes but these methods are typically not very efficient and require expensive components with high loss.
There is a need for methods and systems that enable the combining of laser diodes.